13 Jan 2010

Finding domain names with Node.js

I’m working on some ideas for finance or news software that deliberately updates infrequently, so it doesn’t reward me for reloading it constantly. I came up with the name “microhertz” to describe the idea. (1 microhertz ≈ once every eleven and a half days.)

As usual when I think of a project name, I did some DNS searches. Unfortunately “microhertz.com” is not available (but “microhertz.org” is). Then I went off on a tangent and got curious about which other SI units are available as domain names.

This was the perfect opportunity to try node.js so I could use its asynchronous DNS library to run dozens of lookups in parallel. I grabbed a list of units and prefixes from NIST and wrote the following script:

var dns = require("dns"), sys = require('sys');

var prefixes = ["yotta", "zetta", "exa", "peta", "tera", "giga", "mega",
  "kilo", "hecto", "deka", "deci", "centi", "milli", "micro", "nano",
  "pico", "femto", "atto", "zepto", "yocto"];

var units = ["meter", "gram", "second", "ampere", "kelvin", "mole",
  "candela", "radian", "steradian", "hertz", "newton", "pascal", "joule",
  "watt", "colomb", "volt", "farad", "ohm", "siemens", "weber", "henry",
  "lumen", "lux", "becquerel", "gray", "sievert", "katal"];

for (var i=0; i<prefixes.length; i++) {
  for (var j=0; j<units.length; j++) {
    checkAvailable(prefixes[i] + units[j] + ".com", sys.puts);
  }
}

function checkAvailable(name, callback) {
  dns.resolve4(name).addErrback(function(e) {
    if (e.errno == dns.NXDOMAIN) callback(name);
  })
}

Out of 540 possible .com names, I found 376 that are available (and 10 more that produced temporary DNS errors, which I haven’t investigated). Here are a few interesting ones, with some commentary:

• exasecond.com – 32 billion years
• petasecond.com – 32 million years
• petawatt.com – can be produced for femtoseconds by powerful lasers
• terapascal.com
• gigakelvin.com – possible temperature of picosecond flashes in sonoluminescence
• giganewton.com – 225 million pounds force
• gigafarad.com
• kilosecond.com – 16 minutes 40 seconds
• kilokelvin.com – 1340 degrees Fahrenheit
• centiohm.com
• millifarad.com
• microkelvin.com
• picohertz.com – once every 31,689 years
• picojoule.com
• femtogram.com – mass of a single virus
• yoctogram.com – a hydrogen atom weighs 1.66 yoctograms
• zeptomole.com – 602 molecules

To get the complete list, just copy the script above to a file, and run it like this: node listnames.js

Along the way I discovered that the API documentation for Node’s dns module was out-of-date. This is fixed in my GitHub fork, and I’ve sent a pull request to the author Ryan Dahl.